X combustion m methodi and apparatus



' A ril 10, 1928. 1,665,344 v. z. CARACRISTI COMBUSTION METHOD AND APPARATUS Filed Dec. 23, 1922 WITNESS Patented Apr. 10, 1928.

- UNITED STATES PATENT OFFICE.

VIRGIN'IUS Z. UARACRISTI, 0F BRONKVILLE, NEW YORK, ASSIGNOR TO LOCOMOTIVE PULVERIZEI) FUEL COMPANY, A CORPORATION" 01 DELAWARE. I

COMBUSTION METHOD AND APPARATUS.

Application filed December 23,1322. Serial No. 608,626.

My invention relates to combustion methods and apparatus. The invention is concerned with the burning of diverse fuels in one and the same furnace, and especially with the burning of pulverized fuel (such as powdered coal) in conjunction with other fuel, particularly fuel gas. I aim, in par ticular, to secure certain advantages as respects the operation of the furnace and the combustion of both fuels by burning other fuel in conjunction with powdered coal.

How these and various other advantages can be realized through my invention will appear from mv description hereinafter of the best way of carrying out the invention now known to me which is illustrated by the accompanying drawing.

The figure shows a somewhat diagrammatic vertical section through a steam boiler furnace, illustrating the application of my invention to this field ofnse.

The principal combustion zone of the furnace here shown is in a chamber 1 at the left-hand side of the boiler setting, with one or more pulverized fuel burners 2 for directing a fuel and air stream 3 downward therein, adjacent the front wall l, and with exit upward and toward the rear, at 5, into the boiler space 6 at the right-hand side of the setting. In the front wall 4, at various heights, are damper-controlled intakes 7 through which additional air can be admitted, to aid combustion of the fuel and to form a sort of cooling blanket in front of the descending stream 3, for protecting the wall from the intense heat. The flaming air and fuel stream 3 descends in the front of the-combustion chamber 1. till its momentum is overcome by the draft and the accrctions of air introduced at 7, and then reverses and ascends in the rear of the combustion chamber to the exit at 5. Passing into the boiler space 6 in the right-hand side of the setting, the products of combustion traverse the heating surfaces of the boiler (here shown as a water tube boiler of the Stirling type), and finally escape through the damper-controlled opening 10 into the flue 11 leading to the stack.

In practice, the draft and the fuel and air admission at 2 and 7 are generally so regulated and correlated that the air and fuel stream 3 bends rearward and upward at such a height as to afford (as here shown) a cooling zone 12 in the bottom of the cornbustion chamber 1. As a result, falling particles of ash or slag are cooled below fusion temperature before they reach the furnace floor 13, so that they do not coalesce and run together into a hard, solid mass, but remain loose and easy to remove. Cooling in this zone 12 may be effected largely by a sort of cooling blanket formed beneath the stream 3 (or beneath its descending column, especially) by the air introduced at 7.

As here shown, provision is made for burning fuel gas in the furnace, in combination with the powdered fuel. For this latter purpose, fuel gas introduced by means of a gas burner 15 (usually along with more or less air for combustion) may be allowed to come in contact and mingle with the pulvcrized fuel stream 3, and join in its combustion. Preferably, this fuel gas is introduced beyond the air blanket from the intakes 7. In the present instance, the gas burner 15 is arranged to direct the fuel gas into the lower region of the combustion chamber 1 in a lateral. stream 16, beneath and against the pulverized fuel stream 3 at the region of flexure of the latter. shown. the fuel gas burner 15 discharges from the rear of the combustion chamber forward, through an auxiliary chamber 17 situated in the right-hand side of the boiler setting, directly under the boiler space 6. This auxiliary chamber 17 is separated from the superjacent boiler space by a refractory arch 18 (surmounted by a sort of bridge wall 19 that shelters the lower boiler drum), and opens into the lower region of the combustion chamber 1 from the rear side of the latter. The fuel gas stream 16 thus intro duced by the burner 15 issues from the chamber 17 against the lower side of the ascending pulverized fuel stream 3, counter to the rearward movement of the latter (and its subjacent blanket of air from the intakes 7) at and beyond the point of flexure or reversal.

It will be seen, therefore, that the relatively cool gas stream 16 serves as a continually renewed cool blanket beneath and behind the flaming powdered fuel stream 3, chilling the falling slag and ash particles (and thus increasing the effectiveness of the cooling zone 12), and also protecting the rear wall of the combustion chamber at 19. When this stream 16 is introduced from the rear, as here shown, its cooling power is naturally greatest in the rear portion of the coolingzone 12 (beneath and behind the ascending column of the flaming stream 3), in thevery region where the cooling blanket formed by the air admitted at 7 tends to become ineffective. Moreover, this accre tion of fuel to the stream 3 at this point allows more liberal admission of air at the lower intakes 7, so as to assure an ample blanket of cool air beneath the descending column of the-stream 3, in front of the gas stream blanket 16. V

As to the gas stream 16 itself, it is first heated and ignited by incandescent particles of coal and slag falling into it from the powdered fuel stream 3 (as well as by conduction and radiation), so that when it actually encounters the stream 3, the gas is already burning. Striking the rear side of the air and powdered coal stream 3 more or less at right angles, as it does, the gas stream 16 exerts a drag on this side of the stream 3. Thus swirls and eddies are set up in and beyond the junction, and thorough intermixture of the air, gas, and incandescent solid particles is brought about.

The charaeterfof the stream 16 may vary considerably: thus it may consists, on the one hand, of a; very rich gas; or, on the other hand, of a: low-grade gas,so poor in combustible constitutents', even, as to be incapable of burning by itself without the re generative heating and recurrent ignition effect of the falling incandescent fuel and ash or slag particles, the flaming stream 3,

-or the hot refractories of the furnace set in conjunctionwith other fuel, which comprises directing a pulverized fuel stream downward at one side of a combustion chamber having an outlet in an upper part, to

outlet in an upper part for products of combustion means for introducing a down wardly directed pulverized fuel stream, to descend at one side of the chamber, and for turning it upward to said exit; means for introducing air at the same side of said chamber as said pulverized fuel stream, to form a cooling blanket in front of and be neath the descending portion of said stream, and to aid combustion; and means for introducing another fuel stream into the op posite side of the chamber, to form a cooling blanket beneath and alongside of the ascending portion of the pulverized fuel stream, and to join in the combustion of the latter.

3. Apparatus of the character described comprising a combustion chamber with an outlet in an upper part for products of combustion; means at one side of the chamber for introducing a dowmvardly directed stream of pulverized coal and air for combustion, to descend therein, and for turning it upward to said outlet; and means for introducing a stream of fuel gas from the other side of the chamber.

In testimony whereof, I have hereunto signed my name.

VIRGINIUS Z. CARACRISTI. 

